The invention pertains to a valve assembly which, while useful in many environments, is particularly adapted for use in injection mold apparatus. Such apparatus typically comprises a mold body including first and second body members having respective opposed first and second interface surfaces. The body members are releasably mounted in abutment with each other along the interface surfaces. At least the first of the body members has at least two spaced apart mold cavities disposed at least partially in that body member. These mold cavities are designed for the formation of different elements to be molded. Flowable material is injected into the mold cavities through channels in the interface surface. For example, these channels may include an inlet channel and a pair of branch channels each extending from the inlet channel to a respective one of the mold cavities.
Although the second body member could be simply an abutment member used to close the open sides of the channels, it more typically has formations in its interface surface which register with those of the opposed interface surface of the first body member. Thus, each of the mold cavities may have first and second portions formed in the first and second body members respectively and opening through their interface surfaces so that, when the body members are properly mounted in abutment along the interface surfaces, these cavity portions register with each other to form complete mold cavities. Likewise, the channels of the first body member register with similar channels in the second body member to form generally tubular flowaways, known as "runners," for the molten or flowable material to be molded.
As previously mentioned, each such mold usually includes several cavities for the molding of distinct parts. As also previously mentioned, flowable material may be introduced into these various cavities through a common inlet flowway or "runner" comprising the registered inlet channels of the first and second body members. This allows for simultaneous formation of more than one type of part or article with but a single injection of flowable material. However, in some instances, it may be necessary, to fill a particular order, to mold an unequal number of the various types of parts or articles which the particular mold apparatus is designed to form. In such instances, it is necessary either to waste material by making an equal number of all parts, some of which will then be unused, or to attempt to plug the runner leading to that cavity from which the lesser number of parts is to be formed.
The first of these alternatives is obviously undesirable because it is wasteful. The second is equally undesirable for other reasons. In particular, extensive machining of the mold body member in question is necessary with conventional techniques. Also, the use of conventional "shut offs" or "block offs" requires repeated emplacements, removals and replacements of parts. These two results are not only time consuming and bothersome, but both pose a substantial danger of damage to the smoothly finished interface surfaces and/or the precisely machined channels and mold cavities opening through those interface surfaces.